Parallel to structural economic changes homelessness has become publicly more visible and has received increased media attention in Western industrialized countries. Most studies on mental illness and homelessness in recent years were carried out in North America but only few studies in Europe have dealt with these issues. The goals of the present study were (1) to assess alcohol abuse and dependence as well as other mental disorders in a representative sample of homeless men in Munich using reliable methods of case identification (Structured Clinical Interview for DSM-IV (SCID)), (2) to compare homeless alcoholics with homeless non-alcoholics in our sample on relevant variables, and (3) to compare our data from the Munich sample with data obtained by others. According to our results, the life-time prevalence of any SCID-DSM-IV Axis I diagnoses was 93.2% and the lifetime prevalence of substance use disorder was 79.6%. The single most prevalent diagnosis among homeless males in Munich was alcohol dependence (life-time 72.7%); alcohol abuse (life-time 5.5%) and drug abuse/dependence were considerably lower in prevalence (life-time 19.1%) (weighted data). A higher rate of psychotic disorders was found for non-alcoholic homeless men. Data show that alcoholism and its consequences were more severe in the Munich as compared to North American samples. Homeless alcohol dependent men showed a high comorbidity with other mental disorders (life-time) such as mood disorders (36.4%), anxiety disorders (16.4%), drug abuse/dependence (18.9%) and psychotic disorders (4.5%). Of those with alcohol dependence at some time during their life 59.1% had experienced at least one other life-time mental disorder. Alcohol-related behavioral patterns and symptoms as well as general social functioning are described. Considering the very high prevalence of alcohol dependence (frequently in combination with other mental disorders), the participation in alcohol rehabilitation and other services as well as self-help groups was rather low among Munich homeless alcoholics. Currently homeless men in Germany are adequately supplied with food, clothes, and shelter but psychiatrically (and medically) neglected. Existing concepts and programs for dealing with these problems need to be implemented.